Electronic systems, such as memory systems, can experience a number of events, such as voltage changes, switching events, and the like. For example, voltages on the lines of a bus, such as a data bus of a memory system, can change. The voltages of registers, such as data registers of a memory system, can change as a result of the data values in the registers changing. In some examples, memory systems can experience switching events associated with sensing (e.g., reading) memory cells programmed to a particular state.
Memory systems may be implemented in electronic systems, such as computers, cell phones, hand-held electronic devices, etc. Some memory systems, such as solid state drives (SSDs), embedded Multi-Media Controller (eMMC) devices, Universal Flash Storage (UFS) devices, and the like may include non-volatile storage memories for storing host (e.g., user) data from a host. Non-volatile storage memories provide persistent data by retaining stored data when not powered and may include NAND flash memory, NOR flash memory, read only memory (ROM), Electrically Erasable Programmable ROM (EEPROM), Erasable Programmable ROM (EPROM), and resistance variable memory, such as phase change random access memory (PCRAM), three dimensional cross-point memory (e.g., 3D XPoint), resistive random access memory (RRAM), ferroelectric random access memory (FeRAM), magnetoresistive random access memory (MRAM), and programmable conductive memory, among other types of memory.
Memory cells can be arranged in an array architecture, and buffers with a set of registers can be coupled to the array such that data can be read from the array to the registers for subsequent transmission to the host or host data can be received at the registers and subsequently written to (e.g., programmed in) the array.
Memory cells can be programmable to a number of different data states corresponding to one or more data units (e.g., bits). As an example, some memory cells, such as some resistance variable memory cells, can be programmed to low resistance state, corresponding to a low threshold voltage (Vt) state or a high resistance state, corresponding to a high Vt state. In some examples, a resistance variable cell in a lower resistance state can be said to be in a set state, corresponding to a set Vt distribution (e.g., encoded as a logical 1), and a resistance variable cell in a higher resistance state can be said to be in a reset state, corresponding to a reset Vt distribution (e.g., encoded as a logical 0).
The state of a memory cell can be sensed by, for example, determining whether the cell changes its resistance state (e.g., experiences a switching event) in response to applying a sensing voltage, that may be referred to as a read voltage or a demarcation voltage, to (e.g., across) the cell. For example, memory cells having Vts less than the sensing voltage might experience a switching event, whereas memory cells having Vts greater than the sensing voltage might not. As such, the sensing voltage can be selected to be greater than the Vts corresponding to the set Vt distribution and less than the Vts corresponding to the reset Vt distribution so that memory cells that are in the set state experience a switching event in response to the sensing voltage.